Dyeable polypropylene fibers containing copolymers of acrylamides



United States Patent U.S. Cl. 260-895 34 Claims ABSTRACT OF THE DISCLOSURE Polypropylene fibers and articles of excellent dye afiinity are provided by blending amorphous copolymers of acrylate, methacrylate, vinly pyridine and N-substituted acrylamide monomers with copolymerizable ethylenically unsaturated monomers.

This application is a continuation of our co-pending application Ser. No. 6,598, filed Feb. 4, 1960, and now abandoned.

This invention relates to polypropylene articles and fibers. More particularly, this invention relates to substantially crystalline polypropylene fibers which exhibit excellent dye affinity and fastness properties as well good resistance to oxidation and weathering. In a more specific aspect, this invention relates to polypropylene fibers which are modified with copolymers of acrylic or methacrylic esters, vinyl pyridines and N-substituted acrylamides.

It is well-known that polypropylene, particularly the polypropylene which is partially or completely crystalline, can be melt spun into synthetic fibers having unusual physical properties. This polymer is, however, subject to inherent disabilities which greatly restrict its utility in the fabrication of general purpose fibers. For example, a high-molecular-weight, fiber forming, crystalline polyolefin such as polypropylene, is a relatively insoluble, chemically inert, hydrophobic material. Since it is not readily permeable to water, it cannot be dyed satisfactorily by the ordinary dyeing procedures. Since it is relatively inert chemically, it cannot be permanently dyed even with hydrocarbon soluble dyestuffs. Furthermore, substantially crystalline polypropylene yarns and fibers cannot be dyed readily with a wide variety of dispersed, direct, premetallized, and acid-type dyes, nor can such yarns and fibers be dyed to deep shades having good light and gas tastness. Moreover, the susceptibility of polypropylene fibers to oxidative degradation, instability toward ultraviolet light and poor weathering characteristics have further limited their utility. Hence, it is most desirable to obtain fibers free from the above-mentioned disabilities in order to increase their value in the textile field.

The problem of obtaining polypropylene fibers having the high tenacity, low elongation and other excellent properties characteristic of such fibers without the accompanying undesirable limitations described above, has plagued prior art workers in this field for many years. However, with the development of the instant invention, we have been able to furnish such a polypropylene fiber.

Accordingly, it is an object of this invention to provide polypropylene articles and fibers having improved dye affinity.

Another object of this invention is to provide polypropylene yarns and fibers with greatly improved dyeing characteristics so that they can be dyed readily with a wide variety of dispersed, direct, premetallized, and acidtype dyes which normally will not dye unmodified polypropylene.

Another object is to provide partially or completely crystalline polypropylene yarn and fibers which can be dyed to deep shades with excellent light and gas fastness.

Still another object of this invention is to provide poly propylene yarns and fibers having greatly improved resistance to oxidation and weathering in addition to excellent physical properties.

Further objects of the invention will become apparent throughout the following description.

One successful method which we have developed for providing polypropylene fibers exhibiting excellent dye affinity, light and gas fastness and resistance to oxidation and weathering involves the use of polymeric modifiers containing only specified units, i.e., those derived from specific acrylates, methacrylates, vinyl pyridines and N- substituted acrylamides. It has now been found that copolymers containing these units in combination with other units which ordinarily do not improve the dye aifinity of polypropylene fibers will impart excellent dye affinity, light and gas fastness and resistance to oxidation and weathering to said fibers, provided the percentage composition of the copolymer is kept within certain specified limits. Contrary to expectations, it has been found that the latter units do nOt adversely affect the dye afiinity and other valuable properties of polypropylene fibers mentioned above, as long as the copolymer contains at least 25 mole percent of acrylate, methacrylate, vinyl pyridine or N-substituted acrylamide units as hereinafter defined.

In accordance with this invention it has been found that polymeric blends of polypropylene and about 1 to about 25% and more preferably about 5 to about 15% by weight, based on the blend, of one or more copolymers containing at least 25 mole percent of one or more of the types of acrylate, methacrylate, vinyl pyridine or N-substituted acrylamide units, as hereinafter described, can be spun into high strength fibers and yarns having the same percentage composition which fibers exhibit excellent dye afiinity for dispersed, premetallized or acid-type dyes. The dyed materials obtained thereby exhibit excellent light and gas fastness and unexpectedly good oxidative stability.

The invention provides melt extruded polypropylene articles and melt spun polypropylene textile fibers of excellent dye affinity containing a copolymeric modifier which is a copolymer of at least 25 mole percent of one or more acrylate, methacrylate, vinyl pyridine or N- substituted acrylamide monomers copolymerized with one or more ethylenically unsaturated monomers.

The discovery that certain polymeric blends of crystalline polypropylene with copolymers of acrylic or methacrylic esters can be spun into high strength fibers and yarns having excellent aflinity for dispersed and premetallized dyes as well as excellent light and gas fastness was quite surprising since it could not have been predicted from the prior art. According to the prior art, a polymer containing all methylmethacrylate units, i.e., poly(methy1- methacrylate), when used as a modifier for acrylic fibers, such as acrylonitrile fibers, imparts only a low aflinity for dispersed dyes and, even so, the dyed materials obtained thereby exhibit very poor light fastness.

Although unmodified polypropylene shows virtually no afiinity for dyestuifs, it can be dyed with some dyes to weak shades having, however, very poor fastness properties as mentioned hereinbefore. Surprisingly, it has been found that the shades produced by a given dye on the unmodified polypropylene yarn and on the modifiers themselves was quite d-ifferent from the shades produced by the same dye on the modified polypropylene yarns of this invention. This unpredictable result indicates that the fibers spun from the polymeric blends described above a possess characteristics which ordinarily would not have been expected in fibers spun from simple mixtures of polymeric materials. In this connection, it was also discovered that the modified polypropylene fiber-s described herein were much more resistant to oxidative degradation than fibers obtained from unmodified polypropylene.

The modified polypropylene fibers of this invention are also more stable toward ultraviolet light and weathering conditions than unmodified polypropylene fibers. The reason for the increased stability of the modified polypropylene fibers toward oxidation, light and weathering is not completely understood. It is possible, however, that free radicals generated from the copolymeric modifiers combine with free radicals produced from the polypropylene to prevent chain reactions which would otherwise result in rapid deterioration of the polyolefin. It is possible that the copolymeric modifiers may also be effective in absorbing actinic radiant energy which otherwise could activate free-radical mechanism of decomposition in the polypropylene.

The modified polypropylene fibers and yarns may be further stabilized against thermal breakdown and weathering with any of the conventional stabilizers for polyolefins. It is usually convenient to add such stabilizers to the polymeric blends before spinning into fibers.

The modified polypropylene fibers of this invention may be drawn to give yarns having the same high tenacities, low elongations and other excellent properties found in unmodified polypropylene fibers and yarn. This is quite surprising, since the copolymers of acrylic esters, methacrylic esters, vinyl pyridines and N-substituted acrylamides are substantially noncrystalline, or amorphous, when prepared by conventional methods and, as a result, give fibers which possess low tenacities, high shrinkage properties, and no commercial value. It would have been predicted, contrary to fact, that these materials, when used to modify polypropylene f-or fibers and yarn, would have deleteriously afiected the properties of the yarn.

Another unpredictable feature of this invention is the fact that the copolymers used to modify polypropylene could not be used satisfactorily to modify polyolefin fibers in general. For example, when these modifiers are incorporated into high density or into high density or into conventional polyethylene, they are substantially incompatible. Thus, a blend of polyethylene and our copolymeric modifier-s on melt spinning, gives fibers which are badly segmented. When these fibers are drafted, fibrillation will result, giving a substantially useless product in contrast to the polypropylene fibers of our invention which show no fibrillation when drafted.

Further-more, copolymers containing less than 25 mold percent of the acrylate, methacrylate, vinyl pyridine or N-substituted acrylamide units, for example, an 80/20 styrene/N,N-diphenylacrylamide copolymer, were either incompatible with the polypropylene or did not show improved dye affinity in comparison with the unmodified polypropylene.

According to the practice of this invention, the mono meric units which must be present in the copolymeric modifier in amounts of at least 25 mole percent are those derived from (1) acrylates and methacrylates having the formula:

oH2= J( i-oR wherein R is hydrogen or methyl and R is an alkyl, alkoxyalkyl, cycloalkyl, aralkyl or aryl radical desirably containing 1 to 12 carbon atoms, (2) vinyl pyridines having the formula:

4 wherein R is hydrogen or methyl, R is a lower alkyl group desirably containing 1 to 4 carbon atoms, n is an integer from 0 to 4-, and (3) N-substitu-ted acrylamides having the formula:

I! 0H;=o-oN Rut wherein R is hydrogen or a lower alkyl group desirably containing 1 to 4 carbon atoms, R is hydrogen or an alkyl, cycloalkyl aralkyl or aryl group desirably containing 1 to 18 carbon atoms and R is an alkyl, cycloalkyl, aralkyl, or aryl group desirably containing 1 to 18 carbon atoms. Suitable monomers included within the above formulas are exemplified by methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert.-butyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-vinyl pyridine, 3-vi-nyl pyridine, 4-vinyl pyridine, 5-ethyl-2-vinyl pyridine, 2-methyl-5-vinyl pyridine, 2-methyl-6-vinyl pyridine, 2,4-dimethyl-6-vinyl pyridine, 5-propyl-2-vinyl pyridine, S-isobutyl-Z-vinyl pyridine, 2-isopropenyl pyridine, N-isopropylacrylamide, N-isopropylmethacrylamide, N,N- dimethylacrylamide, N-phenylacrylamide, N-cyclohexylacrylamide, N-butylacrylamide, N,N-diethylacrylamide, N -ethylacrylamide, N-methylacrylamide, N- methyl-N-phenylacrylamide and N-dodecylac-rylamide.

The monomeric units which are described above are present in the form of a copolymer with units which ordinarily do not improve the dye afiinity of polypropylene fibers. Monomeric units of this later type include those derived from one or more diiferent monomers which are copolymerizable with the acrylates, methacrylates, vinyl pyridines or N-substituted acrylamides set forth hereinbefore, i.e. different unsaturated, polymerizable compounds containing one or more CI-L=C groups or more particularly, one or more CH =C groups. Useful copolymers then, can be composed of two or more different types of acrylate, methacrylate, vinyl pyridine or N-substituted acrylamide units, as described above, in combination with other monomeric units such as those derived from any of the well-known ethylem'cally unsaturated polymerizable monomers such as vinyl esters, amides, nitriles, ketones, halides, ethers, nap-unsaturated acids or esters thereof, olefins, diolefins and the like, as exemplified by acrylonitrile, methacrylonitrile, styrene, a-methyl-styrene, vinyl chloride, vinylidene chloride, methyl vinyl ketone, vinyl acetate, fumaric, maleic and itaconic esters, 2-chloroethyl vinyl ether, methylenemalonitrile, acrylic acids, methacrylic esters, N-vinylsuccinimide, N-vinylphthalimide, N-vinylpyrrolidone, butadiene, isoprene, vinylidene cyanide and the like. It is obvious that the nature of the different polymerizable, ethylenically unsaturated compound which is copolymerized with the acrylates, methacrylates, vinyl pyridines and N- substituted acrylamides to form the modifier is subject to wide variation. The truly important feature of the modifier is that the one or more acrylate, methacrylate, vinyl pyridine or N-substituted acrylamide units of the type described above be present therein in amounts of at least 25 mole percent and, more preferably, in amounts of at least 50 mole percent. Furthermore, it is desirable that these units be present in a concentration of about 1 to about 25% by weight and, more preferably, about 5 to about 15% by Weight, based on the fiber or article or on the blend from which the fiber or article is fabricated to give fibers or articles having the above-mentioned charaeteristics.

The copolymeric modifiers of this invention then, can be described as containing the recurring units:

wherein A is at least one member selected from the group consisting of (l) acrylate-methacrylate units having the structure:

containing 1 to 12 carbon atoms, (2) vinyl pyridine units having the structure:

wherein R is hydrogen or methyl, R is a lower alkyl group desirably containing 1 to 4 carbon atoms and n is an integer from to 4, and (3) N-substituted acrylamide units having the structure:

wherein R is hydrogen or a lower alkyl group desirably containing 1 to 4 carbon atoms, R and R are hydrogen, alkyl, cycloalkyl, aralkyl or aryl groups desirably containing 1 to 18 carbon atoms, except that R and R are never hydrogen at the same time, Z is the residue of a different unsaturated, polymerizable compound containing one or more -CH=C or CH C groups and x and y are integers which will provide copolymers having a molecular weight of at least 1000.

Those radicals which can be present in the ester group of the monomeric acrylate or methacrylate, the lower alkyl group of the vinyl pyridine or in the nitrogen substituents of the N-substituted acrylamides, as described by R, R R and R respectively, are subject to wide variation. Suitable R radicals include, for example; methyl, ethyl, n-propyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, nonyl, lauryl, dodecyl, cyclopentyl, cycloheptyl, cyclohexyl, trimethylcyclohexyl, benzyl, phenylhexyl, phenyl trimethylphenyl, diphenyl, methoxyethyl, ethoxybutyl, methoxylauryl, ethoxyethyl and the like. Suitable R radicals include, for example; methyl, ethyl, propyl, n-butyl, i-butyl, and the like. Suitable R and R radicals include, for example; methyl, ethyl, n-propyl, i-propyl, i-butyl, pentyl, phenyl, cyclohexyl, benzyl, u-naphthyl, dodecyl, octadecyl, lauryl and the like.

The monomeric units described above may comprise less than the preferred 50 mole percent, e.g., 40, 30 or even 25 mole percent of the polymeric modifier, but mole percentages of at least 50 percent are desirable since, when less than 50% of these units are present in the modifier, larger amounts of said modifier, based on the weight of the polypropylene blend, must be employed in order to impart the desirable characteristics described in this invention.

It has been found that blends of crystalline polypropylene with the polymeric modifiers described can be melt spun into high strength yarns which can be dyed to deep, light and gas fast shades by means of dispersed, direct, premetallized, and acid-type dyes. The dyeing process can be carried out using conventional procedures either with or without carriers. The polypropylene blends can contain from about 1 to 25% or more, by weight of the copolymeric modifier, although the preferred concentration of modifier is from 5 to However, there are special situations which may warrant the use of 30 or perhaps even 40% by Weight based on the blend, of certain of the copolymeric modifiers disclosed. Furthermore, even though as little as 1% by Weight based on the blend, of the specified copolymeric modifiers will impart dye affinity to the fibers, it is preferred that amounts of at least 5% be employed particularly where deep shades are desired. Polypropylene blends of this type can be melt spun at temperatures ranging from 25 to 65 C. lower than are necessary to melt spin pure polypropylene.

Some specific polymeric modifiers useful in the practice of this invention are:

95/5 copolymer ethyl acrylate/Z-chloroethyl vinyl ether /20 copolymer methyl methacrylate/vinyl acetate 50/50 copolymer methyl methacrylate/ styrene 95/ 5 copolymer ethyl acrylate/vinylidene chloride 94/6 copolymer methyl acrylate/vinyl chloride 50/50 copolymer trimethylcyclohexyl acrylate/bis(norcamphanylmethyl) fumarate 90/10 copolymer ethyl acrylate/acrylonitrile 98/2 copolymer methyl methacrylate/ethyl maleate 90/10 copolymer 2-methyl-5-vinyl pyridine/acrylonitrile 80/20 copolymer 5-ethyl-2-vinyl pyridine/vinyl acetate 90/10 copolymer 2,4-dimethyl-6-vinyl pyridine/ethyl fumarate /15 copolymer Z-rnethyl-S-vinyl pyridine/ styrene 50/50 copolymer 2-methyl-5-isopropenyl pyridine/butadiene 50/50 copolymer 2-isopropenyl pyridine/styrene 97/3 copolymer Z-methyl-S-vinyl pyridine/vinyl chloride 65/35 copolymer 2-methyl-5-vinyl pyridine/vinyl pyrrolidone 75/25 copolymer N-methyl methacrylamide/methacrylic acid / 10 copolymer N-isopropylacrylamide/acrylonitrile 5 copolymer N-ethylacrylamide/vinyl acetate 93/7 copolymer N-cyclohexylacrylamide/vinyl chloride Note: The integers given to indicate the copolymer composition are based on mole percent here and throughout the specification.

Blends of crystalline polypropylene with one or more of the polymeric modifiers may be prepared in any desired manner, whether it be mechanical mixing, coprecipitation or other blending method, e.g., they can be prepared at elevated temperatures on rolls, in a Banbury mixer or any other suitable type of processing equipment or they can be prepared by multiple extrusion techniques. The polymeric modifiers can have a molecular weight of 1000 and higher depending on the particular blend properties desired and the blending method employed. It is to be understood, of course, that any copolymeric modifier having a molecular Weight in excess of 1000 which is capable of introducing about 1 to about 25% by weight, based on the blend or on the article of fiber fabricated therefrom, of the described acrylate, methacrylate, vinyl pyridine or N-substituted acrylamide units into the blend is Within the scope of our invention.

Usually, it is preferable to prepare the modified polypropylene compositions from polypropylene having a conditiontd density above 0.90 and an inherent viscosity in tetralin at C. of from 0.9 to 1.2. Conditioned density, as used herein, refers to the density determined on a sample which has been annealed in an attempt to obtain maximum crystallinity. A conventional annealing procedure involves placing the sample in a tube, heating under high vacuum or in a nitrogen atmosphere to just below the softening point, and allowing the sample to cool slowly. Polypropylene having inherent viscosities above 1.2 can be used in preparing the modified compositions, but then it is usually necessary to degrade these compositions thermally to a lower viscosity in order to realize optimum melt spinning characteristics and fiber properties. The temperatures required for this degradation are usually above 300 C. and often result in an appreciable loss of modifier through depolymerization. Polypropylene of inherent viscosity less than 0.9 can be used in preparing modified compositions for melt spinning, but it does not afford fibers having optimum physical properties.

The modified polypropylene compositions described herein may be spun into fibers having the desired characteristics by conventional melt spinning procedures or melt extruded into articles through a suitable die. Furthermore, these modified polypropylene compositions can be formed into the various cross-sections, e.g., cloverleaf, Y-section etc., 'by employing spinnerettes or dies having appropriately shaped orifices.

The following examples are introduced to illustrate but not necessarily to limit our invention.

EXAMPLE 1 Several compositions comprising crystalline polypropylene (inherent viscosity=1.0 and density=0.912) and a 98/2 copolymer methyl methacrylate/ethyl fumarate are prepared by mechanically blending pellets of the two polymeric materials followed by melt extrusion and repelleting of the resulting compositions. These compositions are then melt spun into 34 filament yarns. Knit tubes prepared from these yarns all dye to deep shades with 4-(4'-fi-hydroxyethylanilino)-5-nitro-1,8-dihydroxy anthraquinone and Isolan Red B, a neutral dyeing premetallized dye [Color Index, volume 4, second edition (1956) page 4326], in the aqueous dye baths at boil for 1 hour. Even deeper shades are obtained by using carriers such as benzyl n-butyrate. All samples show excellent fastness to ultraviolet light in a fadeometer for 20 hours.

EXAMPLE 2 Blends of crystalline polypropylene with an 80/20 copolymer methyl methacrylate/vinyl acetate are prepared by melt extrusion of the mechanical mixtures of the two resins. These blands are then melt spun into 34 Knit tubes fashioned from these yarns are readily dyed with 4-(4'-fi-hydroxyethylanilino)-5-nitro-1,8-dihydroxyanthraquinone and Isolan Red B, a neutral dyeing premetallized dye [Color Index, volume 4, second edition (1956) page 4326], as well as with other dispersed and premetallized dyes. Deep shades which are both light and gas fast are easily obtained.

EXAMPLE 3 The procedure of Example 2 is followed using a 5 /50 copolymer methyl methacrylate/styrene in place of the methyl methacrylate-vinyl acetate copolymer. The yarns obtained show tenacities ranging from 4.5 to 7.0 g./den. and can be dyed to deep shades with dispersed and premetallized dyes.

EXAMPLE 4 The procedure of Example 2 is followed using a 90/ 10 copolymer ethyl acrylate/acrylonitrile in place of the methyl methacrylate-vinyl acetate copolymer. Strong yarns having tenacities of 7.25, 5.85 and 4.53 are obtained. All of these yarns dye to deep shades with excellent light fastness.

EXAMPLE 5 The procedure of Example 2 is followed using a 95/5 copolymer ethyl acrylate/vinylidene chloride in place of the methyl methacrylate-vinyl acetate copolymer. Strong yarns are obtained which show excellent dye afiinity. A 94/ 6 copolymer methyl acrylate/ vinyl chloride when used in place of the above copolymer gives similar results.

8 EXAMPLE 6 A mixture of 9 parts of crystalline polypropylene (inherent viscosity=1.05 and density=0.914) and 1 part 95/5 copolymer ethyl acrylate/Z-chloroethyl vinyl ether is prepared by evaporating a toluene solution of the latter onto pellets of the polypropylene in a conical mixer under vacuum. The solvent-free mixture is then melt extruded into /s-inCh rod and then is chopped into pellets having a length of about A; inch. The resulting composition was readily melt spun into 34-filament yarn at a spinning temperature of 230 C. The unmodified polypropylene requires a melt spinning temperature of 280 C. for optimum spinning characteristics. The modified polypropylene yarn obtained above is knitted into a sock or tube which is used in dyeing tests. Excellent dye affinity, especially for dispersed and premetallized dyes is demonstrated by the deep shades with Isolan Red B, a neutral dyeing premetallized dye [Color Index, volume 4, second edition 1956) page 4326], 4-anilino-3-nitrobenzenesulfonamide, 4 (4' methyl-2'-nitrobenzene)-3- methyl-S-pyrazolene, 4- [4- (benzeneazo -benzeneazo] phenol, 1'-amino-4-hydroxy-2-phenoxy-anthraquinone, 4- (4'-nitrobenzeneazo)-N-ethyl-N-fl-hydroxyethyl aniline, 1-methylamino-4-fi-methylethylaminoanthraquinone and 4(4' -fi-hydroxyethylanilino)-5-nitro-1,8-dihydroxyanthraquinone.

Similar results are obtained when a 94/6 copolymer methyl acrylate/vinyl chloride is used in place of the above copolymer.

EXAMPLE 7 A mixture of 9 parts of crystalline polypropylene (inherent viscosity 1.05 and density 0.914) and 1 part of an /20 copolymer 5-ethyl-2-vinyl pyridine/vinyl acetate is prepared by evaporating a toluene solution of the latter onto pellets of the polypropylene in a conical mixer under vacuum. The solvent-free mixture is then melt extruded into /8-lI1Ch rod and then is chopped into pellets having a length of about /s inch. The resulting composition is readily melt spun into 34 filament yarn at a spinning temperature of 265 C. The unmodified polypropylene requires a melt spinning temperature of 280 C. for optimum spinning characteristics. The modified polypropylene yarn is knitted into a sock or tube which is used in dyeing tests. Excellent dye afiinity for dispersed, premetallized, and acid dyes is demonstrated by the deep shades obtained with 4-(4-;8-hydroxyethylanilino)-5- nitro-l,8-dihydroxyanthraquinone, Isolan Red B, a neutral dyeing premetallized dye [Color Index, volume 4, second edition 1956) page 4326], and Wool Fast Blue BL (Colour Index 833).

Other copolymers which give similar results when used in place of the 80/20 copolymer 5-ethyl-2-vinyl pyridine/ vinyl acetate as above are 90/ 10 copolymer 2,4- dimethyl-6-vinyl pyridine/ethyl fumarate and 50/50 copolymer 3-isopropenyl pyridine/butadiene';

EXAMPLE 8 Three blends of crystalline polypropylene with an 15 copolymer 2-methyl-51vinyl pyridine/ styrene are prepared by melt extrusion of the mechanical mixtures of the two resins. These blends are then melt spun into 34 filament yarns having tenacities ranging from 6.2 to 7.8 g./den. and can be dyed to deep shades with Isolan Red B, a neutral dyeing premetallized dye [Color Index, volume 4, second edition 1956) page 4326], and Wool Fast Blue BL (Colour Index 833). Deep shades which are both light and gas fast are readily obtained.

EXAMPLE 9 The procedure of Example 8 was followed using a 10 copolymer 2-methyl-5-vinyl pyridine/acrylonitrile in place of the 85/ 15 copolymer 2-methyl-5-vinyl pyridine/ styrene. Strong yarns having tenacities of 6.35, 5.99,

and 5.10 are obtained. All of these yarns dye to deep shades having excellent light fastness.

EXAMPLE 10 The procedure of Example 8 is followed using a 97/ 3 copolymer Z-methyl-S-vinyl pyridine/vinyl chloride in place of the 85/ 15 copolymer 2-methyl-5-vinyl pyridine/ styrene. Strong yarns are obtained which show excellent dye afiinity.

A 94/6 copolymer 3-vinyl pyridine/vinylidene chloride when used in place of the above copolymer give similar results.

EXAMPLE 1 l The procedure of Example 8 is followed using a 50/50 copolymer 2-isopropenyl pyridine/styrene as the modifier. The modified polypropylene yarns obtained show excellent aflinity for dispersed, premetallized, and acid dyes. Similar results are obtained when a 65/35 copolymer 2- methyl-S-vinyl pyridine/vinylpyrrolidone is used in place of the above copolymer.

EXAMPLE 12 Blends of crystalline polypropylene with an 80/20 copolymer N-methylmethacrylamidelstyrene are prepared by melt extrusion of the mechanical mixture of the two resins. These blends are then melt spun into 34 filament yarns showing tenacities ranging from 4 to 8 g./den. and can be dyed to deep shades with dispersed, premetallized, direct and acid wool dyes.

EXAMPLE 13 The procedure of Example 12 is followed using a 97/3 copolymer N-isopropylacrylamide/vinyl chloride. Strong yarns having tenacities of 7.0, 6.2 and 5.2 g./den. are obtained. All of these yarns dye to deep shades with excellent light fastness. Similar results are obtained using a 95/5 copolymer N-isopropylacrylamide/vinylidene chloride in place of the above copolymer.

Thus, by means of this invention, substantially crystalline polypropylene yarns and fibers having improved dye affinity, excellent light and gas fastness and increased stability may be obtained. The improved polypropylene fibers of this invention may be used in the same manner as conventional polypropylene fibers; for example, they can be woven into wool-like blankets or used in the production of automobile seat covers and marine hawsers.

The invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. Melt spun polypropylene textile fiber exhibiting excellent dye affinity, light and gas fastness, said fiber containing a polymeric modifier which is an amorphous copolymer of at least 25 mole percent of at least one vinyl pyridine monomer having the formula:

wherein R is a member selected from the group consisting of hydrogen and methyl, R is a lower alkyl radical, and n is an integer from to 4, and copolymerized with up to 75 mole percent of at least one monoethylenically unsaturated monomer selected from the group consisting of vinyl alkanoate, vinyl ketone, alpha,beta unsaturated monocarboxylic acid, alphabeta unsaturated m'onocarboxylic acid esters, vinyl ether, vinyl nitrile, alpha-beta unsaturated dicarboxylic acid, alpha-beta unsaturated dicarboxylic acid esters, vinyl halide, vinylidene halide and vinyl aromatic hydrocarbon.

2. Fiber according to claim 1 wherein said vinyl aromatic hydrocarbon is an alkyl substituted vinyl aromatic hydrocarbon.

3. Fiber according to claim 2 wherein said vinyl aromatic hydrocarbon is alpha-methyl styrene.

4. Fiber according to claim 1 wherein said vinyl pyridine monomer is 2-methyl-5-vinyl pyridine.

5. Fiber according to claim 4 containing from about 1 percent to about 25 percent by weight, based on the fiber, of said polymeric modifier.

6. Fiber according to claim 5 wherein said polymeric modifier is an amorphous copolymer of at least 50 mole percent of Z-methyl-S-vinyl pyridine copolymerized with up to 50 mole percent of styrene.

7. Fiber according to claim 1 wherein said vinyl pyridine monomer is 2-vinyl pyridine.

8. Fiber according to claim 7 containing from about 1 percent to about 25 percent by weight, based on the fiber, of said polymeric modifier.

9. Fiber according to claim 8 wherein said polymeric modifier is an amorphous copolymer of at least 50 mole percent of 2-vinyl pyridine copolymerized with up to 50 mole percent of styrene.

10. Melt extruded polypropylene article exhibiting excellent dye aflinity, light and gas fastness, said article containing a polymeric modifier which is an amorphous copolymer of at least 25 mole percent of at least one vinyl pyridine monomer having the formula:

wherein R is a member selected from the group consisting of hydrogen and methyl, R is a lower alkyl radical, and n is an integer from 0 to 4, and copolymerized with up to 75 mole percent of at least one monoethylenically unsaturated monomer selected from the group consisting of vinyl alkanoate, vinyl ketone, alpha,beta unsaturated monocarboxylic acid, alpha,beta unsaturated monocarboxylic acid esters, vinyl ether, vinyl nitrile, alpha,=beta unsaturated dicarboxylic acid, alpha,beta unsaturated dicarboxylic acid esters, vinyl halide, vinylidene halide and vinyl aromatic hydrocarbon.

11. An article according to claim 10 wherein said vinyl aromatic hydrocarbon is an alkyl substituted aromatic hydrocarbon.

12. An article according to claim 11 wherein said alkyl substituted aromatic hydrocarbon is alpha-methyl styrene.

13. An article according to claim 10 wherein said vinyl pyridine monomer is 2-methyl-5-vinyl pyridine.

14. An article according to claim 13 containing from about 1 percent to about 25 percent by weight, based on the article of said polymeric modifier.

15. An article according to claim 14 wherein said polymeric modifier is an amorphous copolymer of at least 50 mole percent of 2-methyl-5-vinyl pyridine copolymerized with up to 50 mole percent of styrene.

16. An article according to claim 10 wherein said vinyl pyridine monomer is 2-vinyl pyridine.

17. An article according to claim 16 containing from about 1 percent to about 25 percent by weight, based on the article of said polymeric modifier.

18. An article according to claim 17 wherein said polymeric modifier is an amorphous copolymer of at least 50 mole percent of 2-vinyl pyridine copolymerized with up to 50 mole percent of styrene.

19. Melt spun polypropylene textile fiber exhibiting excellent dye afiinity, said fiber containing a vinyl pyridine/ styrene polymeric modifier which is an amorphous copoly- 11 mer of at least 25 mole percent of at least one vinyl pyridine monomer having the formula wherein R is a member selected from the group consisting of hydrogen and methyl, R is a lower alkyl radical, and n is an integer of from to 4, copolymerized with up to 75 mole percent of styrene.

20. Fiber according to claim 19 containing from about 1% to about 25% by weight, based on the fiber, of said polymeric modifier.

21. Fiber according to claim 20 wherein said polymeric modifier is an amorphous copolymer of at least 50 mole percent of at least one of said vinyl pyridine monomers.

22. Fiber according to claim 20 wherein said vinyl pyridine monomer is at least one selected from the group consisting of 2-vinyl pyridine, 3-vinyl pyridine, 4-vinyl pyridine, 5-ethyl-2-vinyl pyridine, 2-methyl-6-vinyl pyridine, 2,4-dimethyl-6-vinyl pyridine, 5-propyl-2-vinyl pyridine, 5-iso butyl-2-vinyl pyridine, and 2-isopropenyl pyridine.

23. Fiber according to claim 20 wherein said amorphous copolymer is a copolymer of 85 mole percent Z-methyl- 5-vinyl pyridine and mole percent styrene.

24. Fiber according to claim wherein said amorphous copolymer is a copolymer of 50 mole percent 2-isopropenyl pyridine and 50 mole percent styrene.

25. A melt extruded polypropylene article exhibiting excellent dye atfinity, said article containing a vinyl pyridine/styrene polymeric modifier which is an amorphous copolymer of at least mole percent of at least one vinyl pyridine monomer having the formula wherein R is a member selected from the group consisting of hydrogen and methyl, R is a lower alkyl radical, and n is an integer of from 0 to 4, copolymerized with up to 75 mole percent of styrene.

26. An article according to claim 25 containing from about 1% to about 25% by weight, based on the article, of said polymer modifier.

27. An article according to claim 26 wherein said polymeric modifier is an amorphous copolymer of at least 50 mole percent of at least one of said vinyl pyridine monomers.

28. An article according to 'claim 26 wherein said vinyl pyridine monomer is at least one selected cfrom the group 12 consisting of 2-vinyl pyridine, 3-vinyl pyridine, 4-vinyl pyridine, 5-ethyl-2-vinyl pyridine, 2-methyl-6-vinyl pyridine, 2,4,-dimethyl-6-vinyl pyridine, S-propyl-Z-vinyl pyridene, S-isobutyl-Z-vinyl pyridine, and 2-isopropenyl pyridine.

29. An article according to claim 26 wherein said amorphous copolymer is a copolymer of 85 mole percent 2-methyl-5-vinyl pyridine and 15 mole percent styrene.

30. An article according to claim 26 wherein said amorphous copolymer is a copolymer of 50 mole percent 2-isopropenyl pyridine and 50 mole percent styrene.

31. Melt spun polypropylene textile fi'ber exhibiting excellent dye afiinity, said fiber containing about 1 percent to about 25 percent by weight, based on the fiber of a polymeric modifier which is an amorphous polymeric methyl methacrylate/vinyl acetate copolymer and con taining at least 25 mole percent methyl methacrylate.

32. Melt spun polypropylene textile fiber according to claim 31 wherein said polymeric modifier is an amorphous /20 methyl methacrylate/vinyl acetate copolymer.

33. A melt extruded polypropylene article exhibiting excellent dye afiinity, said article containing from about 1 percent to about 25 percent by Weight, based on the article, of a polymeric modifier which is an amorphous methyl methacrylate/ vinyl acetate copolymer and containing at least 25 mole percent methyl methacrylate.

34. A melt extruded article according to claim 33 wherein said polymeric modifier is an amorphous 80/20 methyl .methacrylate/ vinyl acetate copolymer.

References Cited UNITED STATES PATENTS 2,527,863 10/1950 Webb 260-895 2,682,518 6/1954 Caldwell 260-898 2,688,008 8/1954 Chaney et al 260-895 2,831,826 4/1958 Coover et al 260-898 2,910,451 10/ 1959 Cantwell 260-889 3,003,845 10/ 1961 Ehlers 260-895 3,103,497 9/ 1963 McCarty et a1 260-895 3,115,478 12/1963 Giustiniani et a1 260-895 3,153,680 10/ 1964 Giustiniani et a1 260-874 3,156,743 11/1964 Coover et a1 260-895 2,893,970 7/1959 Caldwell et al. 3,248,359 4/1966 Maloney. 3,312,755 4/1967 C-appuccio et a1 260-859 3,315,014 4/1967 Coover et al 260-895 3,364,281 1/1968 Saito et a1 260-873 FOREIGN PATENTS 218,828 11/1958 Australia.

GEORGE F. LESMES, Primary Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,439 ,066 April 15 1969 Harry W. Coover Jr. et al It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 21, vinly should read vinyl line 32 after "well" insert as Column 3 line 43 cancel "into high density or", second occurrence Column 4 line 38 "CH=C should read -CH=C line 39, "CH =C should read CH =Ci Column 5 lines 3 to 7 the formula should appear as shown below:

l C OR ll 0 Column 5 line 8 "R" second occurrence should read R line 31 "-CH=C or CH C should read -CH=C or CH line 38 "R" first occurrence should read R Column 6 line 50 "of" should read or line 56 "conditiontd" should read conditioned Signed and sealed this 17th day of March 1970 (SEAL) Attest:

EDWARD M.FLETCHER,J'R. WILLIAM SCHUYLER, JR.

Attesting Officer Commissioner of Patents 

